Apparatus for the operation of cold accumulators



Nov. 29, 1955 A. MAETz 2,724,954

APPRATUS FOR THE OPERATION OF COLD ACCUMULATORS Filed April l5, 1952 2 Sheets-Sheet 1 INVENTOR- Azggws Magi; BY

AT TO RN EYS A. MAETZ Nov. 29, 1955 APPARATUS FOR THE OPERATION OF COLD ACCUMULATORS 2 Sheeras--Shedf` 2" Filed April l5, 1951?.

BY an 74M a/M INVENTOR AugusMae ATTORNEYS United States Patent APPARATUS FOR THE OPERATION F COLD ACCUMULATORS August Maetz, Frankfurt am Main, Fechenheim, Germany, assignor to Adolph Messer G. m. b. H., vFrankfurt am Main, Germany, a corporation of Germany Application April 15, 1952, Serial No. 282,357

Claims. (Cl. 62-122) This invention relates to apparatus for the operation of cold accumulators, as it is used in connection with an apparatus for the separation of gasimixtures, and more particularly for the liquefaction and rectification of air; the use of tubular counter-current cold exchangers for this purpose is known. Such exchangers consist of a substantial number of helically disposed pipes of copper or aluminum arranged in parallel, one portion of same being passed by the ow of air in one direction, and the other portion of same being passed by the cold products of the separation process, oxygen and nitrogen, in opposite direction, whereby the cold of theseparation products is given up to the air to be separated.l .It is an outstanding feature of these cold exchangers that the purity of the separation products, as they are delivered by the separation apparatus, is fully maintained. However, such cold exchangers have the disadvantage that the air to be separated, before passing through the cold exchangers, has to be separated from the 4carbon dioxide and the moisture contained therein, which separation takes place in separate apparatus. Therefore another system of cold exchangers has been developed, which is known as the Linde Frnkl recuperators. The cold exchangers of this type are described in Patents Nos. 1,945,634, 2,107,335 and 2,513,306.

The type of such cold exchangers which is mostlyv lin use, is an apparatus.y consisting of corrugated metal strips spirally disposed to form large disks, piled up one upon the other in substantial number. One of each pair of these cold exchangers or cold accumulators is operated by periodically reversing the direction of the flow and by sending at certain intervals the air to be separated through one cold accumulator and the separation products through the other one, and during the following period, vice versa, the separation products through the iirst one and the air to be separated through the other one. The separation products give up their cold on their passage to the cold accumulator, while during the following period the air to be separated passing this cold accumulator in oposite direction will absorb the cold. The moisture and the carbon dioxide, which have been precipitated by the air in the cold accumulator, are vaporised during the following period by the separation products and removed from the cold accumulator. The advantage of this cold exchanging system is therefore, that there is no separate equipment for the removal of the carbon dioxide and the moisture and that this equipment is consequently saved. The disadvantage however is, that the separation products, and more particularly the oxygen are contaminated by the moisture and the carbon dioxide, so that a subsequent purification of the gas may be required.

The principal object of the present invention is to provide a cold exchanger, combining the advantages of the two above mentioned systems of cold exchangers Without including their disadvantages. The above and other objects and the novel features of the invention will be apparent from the following specification and the accompanying drawing, in which:

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Figure 1 is a diagrammatic view partly in elevation and partly in section of a cold accumulator with the reversing valves andinlet and outlet piping for the air to be separated, and the separation products;

Figure 2 is a side elevation of the parts within the cold accumulator, a portion being in section; and

Figure 3 is a perspective view of a portion of one of the elements composing the cold accumulators.

In Figure 1 the shells of two accumulators according to the invention are shown. The compressed air to be separated flows through the conduit 3, passes through the valve 4, which is open and the conduit 5 and arrives at the cold accumulator 1, which it-leaves at the temperature of about 170 C. It then passes through the conduit 6, the valve 7 and the conduit S, in order to get into the air separation apparatus, which may be of the usual, well known type, as shown in the United States Patent No. 1,890,646. Simultaneously, the nitrogen flows from the separation apparatus through the conduit 9 and the valve 10 into the cold accumulator 2, where it gives up its cold and which it leaves through the conduit 11, the valve 12 for passing by the conduit 13 into the gasholder. The nitrogen is usually not required at a high degree of purity. Therefore, it may absorb the moisture and the carbon dioxide deposited in the cold accumulator 2 during the preceding operation period. Such separation products, however, which have to maintain their degree of purity, as for example the oxygen separated from the air, Viiow Without interruption during the periodical reversing 0f the operation and without any manipulations of the valves continuously and constantly from the separation apparatus through the conduits 14 and 15 to the cold accumulators 1 and 2, through which they are conducted by the spirally coiled conduits, of which the drawing shows, for the sake of better clearness, the conduits 16 and 17 only. On their passage, they give up their cold to the cold accumulators 1 and 2. All the conduits are combined again after leaving the cold accumulators in the common conduits 13 vand 19, which are finally combined into one conduit only 20, leading to the oxygen gasholder.

After a predetermined period corresponding to same of the usual cold accumulators, the cold` accumulated in the cold accumulator 1 during the preceding operating period has been absorbed so far by the air passing through same, that any continuation of the process would increase the temperature of the air leaving the cold accumulator. Then the operation of both cold accumulators 1 and 2 is exchanged. For this purpose, the valves 4, 7, 10 and 12 are closed for obtaining rst of all pressure compensation between the cold accumulators 1 and 2 by Way of the conduit 21, the valves 22 and 23 and the conduit 24, and for releasing the remaining overpressure through `the valve 22 into the atmosphere, after having closed the valve 23. After having closed the valve 22, the valves 25, 26, 27 and 28 are opened. Then the compressed air flows through the conduit 3, through the valve 25 into the cold accumulator 2, and after being cooled down within the same, through the valve 26 and the conduit 8 to the separation apparatus. The nitrogen coming from the separation apparatus liows through the piping 29 and the valve 27 into the cold accumulator 1, gives up its cold there and leaves it through the conduit 30, the valve 28 and the conduit 13, for being sent into the nitrogen gasholder. The regulation of the valves may be obtained, for example, by a cam shaft 31. At the end of this operating phase, both cold accumulators are exchanged again in their operation by the corresponding reversion of their valves. The oxygen stream is not touched at all by the manipulations.

Figure 2` shows the lower portion of a cold accumulator, according to the invention, partly in section. Within the shell "Ll, the conduits for the oxygen are spirally rolled up `in various layers around the tubular cylinder 32, `of which the conduits 16 and 17 are only shown by way of example. Each of such conduits, which may be made for example of aluminum, may be equipped with two corrugated aluminum sheet strips with a view to improving the transfer or exchange of cold. The conduit 16 is shown with the strips 16a and 16b and the conduit 17 with the strips 17a and 17b. The pipes are so coiled up in each position that there is a small interspace between the edges of adjacent sheet strips. The distance between two layers of coiled pipes are lled up with helically rolled up corrugated strips, serving for the accumulation of the cold. They form various thin channels passed during one operating period by the nitrogen, giving up its cold to the sheet, and during the next operating period by the compressed air absorbing lthe cold accumulated by the sheets. The strips may 'be combined by rivets for facilitating the rolling up.

Figure 3 shows the design of one layer of coils in natural size in all details. The strip layers consist for example of four such superposed diagonally corrugated aluminum sheets, where the corrugations of two such superposed strips have a different direction. The strips 33 are held together by rivets 34.

At both sides or ends of the cylinder 32 grates 35 are fixed consisting of aluminum casting, to which the ends of the corrugated strips are welded. The conduits 16 and 17 pass through the grates and are welded in clusters into the flanges 36, which are inserted into the branches 37 of the conduits.

In the same way as the process and apparatus are described above as applied to the cold exchange between air and the separation products, this invention can be similarly used for the reversals of cold and heat accumulators between any given gas mixture and one of its separation products, It is obvious that various changes may be made in the details of the above described process and apparatus, without departing from the principles of this invention.

What I claim is:

l. Apparatus for the cold exchange between a gas to be separated by liquefaction and rectification and the separation products comprising a pair of periodically reversible cold accumulators, each having a warm portion and a cold portion, the compressed gas to 'be separated passing through one accumulator from the warm portion to the cold portion and one of the separation products passing through the other accumulator from the cold portion to the warm portion thereof; means for interrupting the ow of said gases at the end of the predetermined period of time and `compensating the pressures in said accumulators, means for exchanging the flows of said gases for other and special conduits within both accumulators for the other separation product to be recovered pure., these separation products passing from the cold portion to the warm portion of the accumulators independently of the flows of the other gases outside of the special conduits, the conduit within the accumulator being helically disposed around a hollow cylinder, and corrugated meta-l -stripsl between successive turns of the coils and having a similar hel-ical contour.

2. Apparatus for the cold exchange between a gas to be separated by liquefaction and rectification and the separation products, as claimed by claim l, the special conduits being provided lengthwise at both sides with corrugated metal strips.

`3. Apparatus for the cold exchange between a gas to be `separated by liquefaction and rectification and the separation products, as defined in claim 1, and in which corrugated metal strips are disposed between and in contact with the coils, and means for securing said strips at the top and at the bottom of the accumulator.

4. Apparatus for cold exchange between a gas to be separated by liquefaction and rectication and the separation products, said apparatus including a casing having an inlet and an outlet, an axially extended coiled conduit within said casing, and a layer of corrugated metal in the form of a similarly coiled helix disposed between successive turns of the coiled conduit.

5 Apparatus as set forth in claim 4 wherein the metal is aluminum and is in contact with said coiled conduit along its longitudinal extent.

References Cited in the le of this patent UNITED STATES PATENTS 2,097,434 De Baufre Nov. 2, 1937 2,107,335 Linde et al Feb. 8, 1938 2,214,672 Hausen Sept. 10, 1940 2,513,306 Garbo July 4, 1950 2,586,207 Collins Feb. 19, 1952 2,648,205 Hufnagel Aug. `11, 1953 FOREIGN PATENTS 276,381 Great Britain Aug. 18, 1927 

